It is often of considerable interest and value to be able to administer substances at predetermined locations all along the gastrointestinal (GI-)tract. The same applies to the possibility of aspirating samples or collect measurement signals from different sensors. It is also of interest to test the local permeability all along the GI-tract to investigate new possibilities to develop pharmaceutical preparations or to obtain a better understanding about the kinetics of a certain drug. It is also possible to sample through the tube for analysis of possible deviations in the composition of the gastric or intestinal juice. It can further be of interest to measure some parameter, e.g. pH, pressure, electrolytes, a chemical compound or enzyme at a specified location along the GI-tract.
Today, a number of capsules are described or are available, which can be swallowed freely (without wire or tube) and which can be tracked telemetrically or by X-ray, isotopes or ultrasound during their ride along the GI-tract. Using this kind of capsules it is possible to deliver an isolated dose of some drug (Hugemann, DE 29 28 477 B2; U.S. Pat. Off.: Casper et al., U.S. Pat. No. 5,170,801 and Kambara et al., U.S. Pat. No. 4,507,115; Hemmati 1969; N.Y. State University 1992) and record and transmit signals for measurement of pH (Wolff and Russ 1960) or pressure (Connell and Rowlands 1960; Barany and Jacobsson 1964; Farrar and Bernstein 1968). It is also possible to aspirate a small volume of liquid (Uchiyama et al. 1980). A special form of telemetric capsule can by choice of suitable module, designed to be installed onto a basic capsule, deliver a single dose of selected drug, aspirate a small volume, or sample a small biopsy from the intestinal mucosa (Lambert et al. 1991). However, all of these capsules suffers from the limitation that they are mobile along the GI-tract and that they cannot deliver dose or aspirate repeatedly or continuously. The subject who has swallowed the capsule will also experience a limited mobility due to the need for telemetric recording.
Solid bodies fitted with a wire for "mooring" in a fixed position have been described for delivery of a drug from one or multiple pills mounted (a) at the end of the wire or along the wire in the GI-tract (U.S. Pat. Off: Millard, U.S. Pat. No. 2,483,098 and Kaslow and Saputo U.S. Pat. No. 2,773,502) or in the form of a capsule for pressure recording (Browning et al. 1981) or a capsule for delivery of physiologically active or diagnostic substances to the gastrointestinal tract (Lindstrom et al. Patent application WO 92/05759 A1). These devices can be locked in a fixed position but cannot deliver a solution, time-control dose delivery/aspiration nor execute these operations repeatedly or continuously during a certain time period or at different positions.
A principle for perfusion of the upper part of the small intestine (Lennernas et al. 1992) is applied using a rather thick tube (diameter 5.3 mm) which is introduced into the intestine under X-ray guidance. The tube contains channels which on one hand allow for inflation of two balloons which lock up one segment of the intestine, on the other hand allow for perfusion of the trapped part of the intestine. In this way is it possible to convey substances in solution and also take back remaining, not absorbed substance or endogenous compounds. The method calls for local anesthesia of the pharynx region and will strongly interfere with the peristalsis and physiology in the GI-tract. Furthermore, the experiments cannot be going on for more than a few hours and only the upper part of the small intestine is accessible (risk for ileus if the thick tube is transported further down into the intestine).
Methods using some form of capsule applied to a tube are described. The so called Watson-capsule (Ferraris Medical Ltd, London, UK), is a solid capsule which is pulled down in the upper small intestine dragging an air-filled tube. It has a very limited application (biopsies in the upper small intestine). Another application is a tube applied with loops in the top which will allow the intestine to get a good grip to pull down the tube. In that way one will obtain a route for application of nutrients into the upper part av the small intestine postoperatively (Bengmark et al. 1989). A similar use has an equipment consisting of a tube with a stabilizing inner thread surrounded by an inflatable balloon (Lauterjung. Patent specification SE 448 671 B). It is introduced in a deflated shape, then filled with liquid to allow transport to the upper small intestine. By increasing the pressure of the liquid the balloon opens and the tube can be used for nutrition. These equipments are not useful for deeper positions. A further application is so called enteroscopy, where a mercury- or air-filled balloon is used to pull down a tube (Deyhle et al. 1972) or a flexible enteroscope (Seensalu 1993). In the first case the tube is utilized for guiding a fiberscope down into the lower part of the small intestine, in the latter the enteroscope is directly used to reach the lower small intestine. These methods are not constructed for administration/aspiration or entrance into the colon and would be very inconvenient for ambulant patients or subjects in normal activity or for administration controlled by the subject itself.